Among water-soluble polymeric compounds, those which, in a state of an aqueous solution, show a special reversible solubility behavior such as precipitation and formation of white turbidity at a temperature higher than the LCST (lower critical solution temperature which is the transition temperature for the hydration and dehydration of temperature-responsive polymer) and dissolution and becoming clear at the temperature lower than the LCST, are called thermally reversible polymers. Thermally reversible polymers are being applied in light-shielding members or adsorbents. However, because the thermally reversible polymer itself can dissolve in water at low temperatures, it has to be insolubilized or immobilized by some method such as by formation of crosslinking or by grafting to a supporting member, in order to make it available for wider application.
Modified thermally reversible polymers have been reported in many research reports or patent publications [Okihiko Hirasa, Sen'i Kobunshi Kenkyusho Hokoku, No. 144, p. 139 (1984); Ko Ka et al., Kagaku Kogaku Ronbunshu, v. 13, p. 518 (1987); Japanese Patent Publication (Kokai) Nos. 250016/1985 and 233184/1985 Japanese Patent No. 1,389,504 etc.]. However, because these prior art polymers still have problems such as poor moldability and poor mechanical properties, application of thermally reversible polymers has been limited.